Barbecue grills of the type which employ a solid fuel, such as charcoal or the like, enjoy widespread use. In general, such barbecue grills comprise a receptacle or bowl which is frequently mounted on legs and wheels to render the same portable. The charcoal or other solid fuel may be placed directly on the receptacle bottom or, more commonly, on a wire grid positioned near the bottom of the receptacle. Another wire grid is removably positioned in the receptacle at its top for retaining the cooking food, and a cover having a top damper may be associated with the receptacle. For efficient control over the combustion rate of the charcoal, it is desirable to provide a damper in the bottom of the receptacle so that an air supply can flow upward through the burning coals. Thus, it is well known to provide damper means in the bottom wall of barbecue grill receptacles and other solid fuel firepots. However, prior barbecue grill dampers have been characterized by a variety of disadvantageous features, such as, high cost, excessive number of parts, difficulty of operation, accumulation of ash waste which hampers operation, difficulty of assembly, use limited to a particular shape of receptacle, and the like.
One form of prior of prior barbecue grill damper and ash rake designed specifically for the curved bottom wall of a hemispheroidal container is shown in U.S. Pat. No. 4,416,248. In that structure, there are three curved, V-shaped arms which must be telescoped in a particular order over a hexagonal center post in order to maintain the same in a particular radial orientation and provide close contact with the curved bottom wall of the receptacle. An operating handle is positioned through an aperture in the center post, a thumb screw is threaded into the center post and a friction washer is retained between the handle and the receptacle bottom to complete that damper assembly.
Other examples of barbecue grill dampers and ash rakes are shown in U.S. Pat. No. 3,667,448, which teaches a lower bowl compartment having a waste-receiving opening formed therein and a rotatable fuel-supporting grill having a depending scraper blade for scraping waste into the opening; and U.S. Pat. No. 3,126,881, which teaches an arcuate fuel-supporting plate rotatably mounted on the bottom of a barbecue bowl and having openings which may be aligned with openings in the bowl bottom to scrape expended coals and waste into a waste container positioned therebeneath, by rotating within fixed rods welded to the bowl bottom.
Various forms of grates positioned at the bottom of other solid fuel burning devices, such as stoves and furnaces, are shown in U.S. Pat. Nos. 744,082; 970,460; and 1,866,959.
The limitations and shortcomings of the representative types of dampers and ash rakes alluded to above, particularly as applied to barbecue grills, will be apparent to those skilled in the art.